/*
 * Copyright � 2002-2011 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

using System.Collections;
using System.Runtime.Serialization;
using Spring.Collections;
using Spring.Util;

namespace Spring.Expressions;

/// <summary>
/// Represents arithmetic subtraction operator.
/// </summary>
/// <author>Aleksandar Seovic</author>
[Serializable]
public class OpSUBTRACT : BinaryOperator
{
    /// <summary>
    /// Create a new instance
    /// </summary>
    public OpSUBTRACT() : base()
    {
    }

    /// <summary>
    /// Create a new instance from SerializationInfo
    /// </summary>
    protected OpSUBTRACT(SerializationInfo info, StreamingContext context)
        : base(info, context)
    {
    }

    /// <summary>
    /// Returns a value for the arithmetic subtraction operator node.
    /// </summary>
    /// <param name="context">Context to evaluate expressions against.</param>
    /// <param name="evalContext">Current expression evaluation context.</param>
    /// <returns>Node's value.</returns>
    protected override object Get(object context, EvaluationContext evalContext)
    {
        object left = GetLeftValue(context, evalContext);
        object right = GetRightValue(context, evalContext);

        if (NumberUtils.IsNumber(left) && NumberUtils.IsNumber(right))
        {
            return NumberUtils.Subtract(left, right);
        }
        else if (left is DateTime && (right is TimeSpan || right is string || NumberUtils.IsNumber(right)))
        {
            if (NumberUtils.IsNumber(right))
            {
                right = TimeSpan.FromDays(Convert.ToDouble(right));
            }
            else if (right is string)
            {
                right = TimeSpan.Parse((string) right);
            }

            return (DateTime) left - (TimeSpan) right;
        }
        else if (left is DateTime && right is DateTime)
        {
            return (DateTime) left - (DateTime) right;
        }
        else if (left is IList || left is ISet)
        {
            ISet leftset = new HybridSet(left as ICollection);
            ISet rightset;
            if (right is IList || right is ISet)
            {
                rightset = new HybridSet(right as ICollection);
            }
            else if (right is IDictionary)
            {
                rightset = new HybridSet(((IDictionary) right).Keys);
            }
            else
            {
                throw new ArgumentException("Cannot subtract instances of '"
                                            + left.GetType().FullName
                                            + "' and '"
                                            + right.GetType().FullName
                                            + "'.");
            }

            return leftset.Minus(rightset);
        }
        else if (left is IDictionary)
        {
            ISet leftset = new HybridSet(((IDictionary) left).Keys);
            ISet rightset;
            if (right is IList || right is ISet)
            {
                rightset = new HybridSet(right as ICollection);
            }
            else if (right is IDictionary)
            {
                rightset = new HybridSet(((IDictionary) right).Keys);
            }
            else
            {
                throw new ArgumentException("Cannot subtract instances of '"
                                            + left.GetType().FullName
                                            + "' and '"
                                            + right.GetType().FullName
                                            + "'.");
            }

            IDictionary result = new Hashtable(rightset.Count);
            foreach (object key in leftset.Minus(rightset))
            {
                result.Add(key, ((IDictionary) left)[key]);
            }

            return result;
        }
        else
        {
            throw new ArgumentException("Cannot subtract instances of '"
                                        + left.GetType().FullName
                                        + "' and '"
                                        + right.GetType().FullName
                                        + "'.");
        }
    }
}
